1. Field of the Invention
The invention relates to a rotor blade set for an electric motor, including a plurality of axially assembled, multi-part and/or single-part blades having circle segment-shaped blade sections, between which radial and circumferentially open recesses are provided for receiving a magnet.
2. Description of the Background Art
Electric motors having blade sets of this type are frequently used as low-power motors in motor vehicles, where they are employed, in particular, as power steering motors or adjustment drives. While the rotor concentrically surrounds the stationary stator in an electric motor as a so-called external rotor motor, the stator is disposed coaxially to the rotating rotor in an internal rotor motor, forming an air gap.
In a permanently excited, brushless DC motor, the rotor has a number of permanent magnets, while the stator includes, for example, a three phase-connected coil winding, which is activated by means of pulse-width modulated currents. If the rotor is provided with the magnets, they may be held on the blade set of the rotor by means of clamping and/or gluing. The blade set comprises a plurality of punch-packed, individual blades (blade laminates).
The assembly of a rotor blade set from single/multi-piece or single/multi-part blades having circle segment-shaped blade sections is known from EP 1 223 658 A1 and from DE 10 2007 024 406 A1. For this purpose, a first single-piece (single-part) blade type has web-like connecting areas between the blade sections on the inner and/or outer circumferential side(s). A second multi-piece (multi-part) blade type comprises, for practical purposes, the individual blade sections not connected to each other. The axially stacked blades are connected to each other in the manner of a punch packed system, with the aid of engaging (bead-like) recesses and projections stamped into the blade sections. Radial, circumferentially open recesses, which are axially aligned with the packed blade stack and form receiving pockets for permanent magnets, are provided between the blade sections.
A rotor is known from DE 103 57 502 A1, which corresponds to U.S. Pat. No. 8,026,648, which is assembled in the axial direction from a blade set made of identically shaped individual blades, magnets inserted into receiving pockets of the rotor being held on projections provided on the narrow sides of the receiving pockets.
In the blade sets known from DE 10 2007 029 719 A1, pocket openings of individual blades carry a clamping clip either on both narrow sides or on only one narrow side, which, however, is always the same side.
A rotor stacked from individual blades, including receiving pockets for magnets, is also known from U.S. Pat. No. 5,581,140. Clamping clips for fixing the magnets by clamping are provided on the longitudinal sides of the receiving pockets, the clamping clips not being provided in each blade position but only in every third or fourth blade position.